Mob store, reportedly (5)
I believe the answer is:
horde
'mob' is the definition.
(I've seen this before)
'store reportedly' is the wordplay.
'store' becomes 'hoard' (hoard is a kind of store).
'reportedly' shows a homophone (sound like).
'hoard' is a homophone of 'HORDE'.
(Other definitions for horde that I've seen before include "Throng, mass" , "Vast multitude" , "Host" , "Large force" , "Great crowd" .)